On calling an end to the sacking of Athens, after a plea on its behalf by two Athenians loyal to Rome, as quoted in The Story of Rome : From the Earliest Times to the Death of Augustus (1900) by Mary Macgregor; also said to be in a translation of Plutarch's works.

No friend ever served me, and no enemy ever wronged me, whom I have not repaid in full.

His self-made epitaph, as quoted in Heroes of History : A Brief History of Civilization from Ancient Times to the Dawn of the Modern Age (2001) by Will Durant; variant translation: "...nor enemy harmed me"

He ought to have worked at the oar before steering the vessel.

Upon being handed the head of his enemy Gaius Marius the Younger[1] (Also translated as: "First you must learn to pull an oar, only then can you take the helm")